package cn.edu.scau.cmi.dengzejun.chapter09;

public class EncryptAndDecrypt {
	public String encrypt(String source ,String password) {
		char[] p = password.toCharArray();
		int n = p.length;
		char[] c = source.toCharArray();
		int m = c.length;
		for (int k = 0;k<m;++k) {
			int mima = c[k] + p[k%n];
			c[k] = (char)mima;
		}
		return new String(c);
	}
	
	public String decrypt(String source ,String password) {
		char[] p = password.toCharArray();
		int n = p.length;
		char[] c = source.toCharArray();
		int m = c.length;
		for (int k = 0;k<m;++k) {
			int mima = c[k] - p[k%n];
			c[k] = (char) mima;
		}
		return new String(c);
	}
}
